1. Field of The Invention
This invention relates to a method for joining metallic members used for joining a porous metallic member and a non-porous metallic member, for example, used for joining a porous aluminum sound-absorbing panel board with metal fitting of said sound-absorbing panel board.
2. Description of The Prior Art
Herefore, there has been porous metalic materials manufactured through various procecces such as powder-sintering, molten metal-foaming, fiber press-forming, and the like. Among them, porous metallic materials having a porosity not less than 30% are useful for sound-absorbing materials.
Previously, a process possible to obtain porous aluminum with a porosity of 30 to 70% by sintering a mixture of aluminum (inclusive aluminum alloys) powder and additional powder having a melting point lower than that of said aluminum powder at a temperature lower than melting point of said aluminum powder in a non-oxidizing atmosphere was developed (Japanese Patent Publication No. 56-11375/81, U.S. Pat. No. 4,283,465).
Said porous aluminum materials are considerably light as compared with non-porous materials because of a porosity of 30 to 70%, and receive wide application such as sound-absorbing materials for various machinery because of excellent acoustic absorptiveness thereof, furthermore it is used abundantly for a sound-absorbing board as constructive materials.
In case such a porous aluminum board is used for a wall, a ceiling or the like in the interior and exterior of the building, it is required to use a large number of porous aluminum members in the shape of flat and rectangular boards. When the porous aluminum members are fixed to a base frame as shown in FIGS. 12 and 13, a porous metallic board 101 is fixed to the base frame 102 in a state in which the porous metalic board 101 is kept on said base frame 102 with screws 103 or adhesives, or combination of them.
However, attaching the porous aluminium members with screws and adhesives, for example in case of the screw clamping shown in FIGS. 12 and 13, the head of said screw 103 is exposed heterogeneously on the surface of the porous aluminum members, therefore there is a problem in that an appearance of the surface becomes unattractive especially in case the porous aluminum member is used as a sound-absorbing panel for an interior decoration. There are other problems in that it is not possible to obtain a sufficient strength, and adhesive property deteriorates with passage of time in case adhesives are used.